Murat Uygun

Lysozyme-Based Antibacterial Nanomotors

An effective and rapid bacterial killing nanotechnology strategy based on lysozyme-modified fuel-free nanomotors is demonstrated. The efficient antibacterial property of lysozyme, associated with the cleavage of glycosidic bonds of peptidoglycans present in the bacteria cell wall, has been combined with ultrasound (US)-propelled porous gold nanowire (p-AuNW) motors as biocompatible dynamic bacteria nanofighters. Coupling the antibacterial activity of the enzyme with the rapid movement of these p-AuNWs, along with the corresponding fluid dynamics, promotes enzyme-bacteria interactions and prevents surface aggregation of dead bacteria, resulting in a greatly enhanced bacteria-killing capability. The large active surface area of these nanoporous motors offers a significantly higher enzyme loading capacity compared to nonporous AuNWs, which results in a higher antimicrobial activity against Gram-positive and Gram-negative bacteria. Detailed characterization studies and control experiments provide useful insights into the underlying factors controlling the antibacterial performance of the new dynamic bacteria nanofighters. Rapid and effective killing of the Gram-positive Micrococcus lysodeikticus bacteria (69-84% within 1-5 min) is demonstrated.

Micromotor-Based Biomimetic Carbon Dioxide Sequestration: Towards Mobile Microscrubbers.

We describe a mobile CO2 scrubbing platform that offers a greatly accelerated biomimetic sequestration based on a self-propelled carbonic anhydrase (CA) functionalized micromotor. The CO2 hydration capability of CA is coupled with the rapid movement of catalytic micromotors, and along with the corresponding fluid dynamics, results in a highly efficient mobile CO2 scrubbing microsystem. The continuous movement of CA and enhanced mass transport of the CO2 substrate lead to significant improvements in the sequestration efficiency and speed over stationary immobilized or free CA platforms. This system is a promising approach to rapid and enhanced CO2 sequestration platforms for addressing growing concerns over the buildup of greenhouse gas.

Self-propelled chelation platforms for efficient removal of toxic metals

Water-powered ligand-modified micromotors that offer efficient ‘on-the-fly’ chelation of heavy metal contaminants are described. The Janus micromotors are prepared by functionalizing Mg/Au microsphere motors with a self-assembled monolayer of meso-2,3-dimercaptosuccinic acid (DMSA). The resulting micromotors propel autonomously in complex environmental and biological matrices, containing chloride and surfactant, obviating the need for external (peroxide) fuel or expensive Pt catalysts. Such self-propelled micromotors act as highly efficient dynamic chelation platforms that offer significantly shorter and more efficient water remediation processes compared to the common use of static remediation agents. The effective decontamination capability of the DMSA-based Janus micromotors is illustrated towards the rapid removal of Zn(II), Cd(II) and Pb(II). Factors influencing the micromachine-enhanced metal chelation process, such as the navigation time and number of motors, have been investigated. High removal efficiencies of ∼100% are obtained for all target metals following 2 min treatment of serum, seawater or lakewater samples spiked with 500 μg L−1 of each heavy metal. The chelation mechanism has been characterized using the Langmuir model, indicating strong interaction and monolayer-type adsorption of the target heavy metals onto the DMSA-binding layer. The new nanomotor concept holds considerable promise towards future metal remediation applications.

Preparation of Laccase Immobilized Cryogels and Usage for Decolorization

Poly(methyl methacrylate-co-glycidyl methacrylate) (poly(MMA-co-GMA)) cryogels were synthesized by radical cryopolymerization technique. Then, laccase enzyme was covalently attached to the cryogel and characterized by using swelling studies and SEM and EDX analyses. Kinetic properties and optimum conditions of the immobilized and free laccase were studied and it was found that of the immobilized laccase was lower than that of free laccase. of the immobilized laccase was increased upon immobilization. Optimum pH was found to be 4.0 for each type of laccase, while optimum temperature was shifted to the warmer region after the immobilization. It was also found that thermal stability of the immobilized laccase was higher than that of free laccase. Immobilized laccase could be used for 10 times successive reuse with no significant decrease in its activity. Also, these laccase immobilized cryogels were successfully used for the decolorization of seven different dyes.

Dye Attached Nanoparticles for Lysozyme Adsorption

In this work, Reactive Blue 15 dye functionalized poly(HEMA) nanoparticles were synthesized for reversible adsorption of lysozyme from its aqueous solution. For this, nano-sized poly(HEMA) nanoparticles were synthesized by the surfactant free emulsion polymerization. Reactive Blue 15 dye then covalently attached to the polymeric structure. These novel dye attached poly(HEMA) nanoparticles were used for the adsorption of lysozyme. Characterization of dye attached nanoparticles was carried out by using FTIR, AFM, and elemental analysis. Incorporation of the dye onto the polymeric structure was demonstrated by FTIR and elemental analysis, while the size and the shape of the nanoparticles were shown by AFM. The incorporated amount of the dye was found to be 70.3 μmol/g nanoparticle with sulphur stoichiometry and it was found that the prepared nanoparticles were in a spherical form and were about 100 nm diameter. Lysozyme adsorption studies were carried out with different conditions (pH, lysozyme concentration, temperature, and ionic strength) and maximum lysozyme adsorption was found to be 630.7 mg/g nanoparticle at pH 7.0 in 25°C medium temperature. Adsorbed lysozyme was desorbed by 1.0 M of NaCl with 96% recovery and synthesized dye-attached nanoparticles were used 10 times without any decrease in their adsorption capacity.

Molecularly imprinted cryogels for carbonic anhydrase purification from bovine erythrocyte

Abstract Molecularly imprinted PHEMAH cryogels were synthesized and used for purification of carbonic anhydrase from bovine erythrocyte. Cryogels were prepared with free radical cryopolymerization of 2-hydroxyethyl methacrylate and methacryloylamido histidine and characterized by swelling degree, macroporosity, FTIR, SEM, surface area and elemental analysis. Maximum carbonic anhydrase adsorption of molecularly imprinted PHEMAH cryogel was found to be 3.16 mg/g. Selectivity of the molecularly imprinted cryogel was investigated using albumin, hemoglobin, IgG, γ-globulin, and lysozyme as competitor proteins and selectivity ratios were found to be 15.26, 60.05, 21.88, 17.61, and 17.42, respectively. Carbonic anhydrase purity was demonstrated by SDS-PAGE and zymogram results.

Boronate affinity nanoparticles for RNA isolation.

In this presented paper, boronic acid incorporated poly(HEMA) based nanoparticles were synthesized for RNA adsorption. For this purpose, poly(HEMA) nanoparticles were synthesized by using the surfactant free emulsion polymerization technique. Then, nanoparticles were modified with 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) and functionalized with phenylboronic acid (PBA). Prepared nanoparticles were characterized with SEM, FTIR and zeta-size. Optimum RNA adsorption conditions were investigated with different pHs, temperatures and initial RNA concentrations in order to determine the maximum RNA adsorption onto poly(HEMA)-IMEO-PBA nanoparticles. It was also studied that, synthesized nanoparticles could be used for 5 successive reuses and adsorption capacity of the nanoparticles decreased only about 5% at the end of the 5 cycles.

Controlled release of curcumin from poly(HEMA-MAPA) membrane

Abstract In this work, poly(HEMA-MAPA) membranes were prepared by UV-polymerization technique. These membranes were characterized by SEM, FTIR, and swelling studies. Synthesized membranes had high porous structure. These membranes were used for controlled release of curcumin which is already used as folk remedy and used as drug for some certain diseases and cancers. Curcumin release was investigated for various pHs and temperatures. Optimum drug release yield was found to be as 70% at pH 7.4 and 37 °C within 2 h period. Time-depended release of curcumin was also investigated and its slow release from the membrane demonstrated within 48 h.

Dye functionalized cryogel columns for reversible lysozyme adsorption

In this study, poly (methyl methacrylate–glycidyl methacrylate) [poly(MMA-GMA)] cryogels were prepared by radical cryocopolymerization of MMA with GMA as a functional comonomer. Reactive Green 19 dye was then attached to the cryogel by nucleophilic substitution reaction, and this dye-attached cryogel column was used for lysozyme adsorption. Characterization of the cryogel was performed by Fourier transform infrared spectroscopy, environmental scanning electron microscopy, Brunauer–Emmett–Teller, and energy dispersive X-ray analysis. Pore size of the cryogels was 15–30 μm and pores were interconnected structure. Attached amount of Reactive Green 19 to cryogel support was calculated as 106.25 μmol/g cryogel. Lysozyme adsorption studies were carried out by using a continuous system. It was found that the maximum amount of lysozyme adsorption (32 mg/g cryogel) obtained from experimental results was found to be approximately same with the calculated Langmuir adsorption capacity (33 mg/g cryogel). Desorption of adsorbed lysozyme was carried out by using 1.5 M NaCl in pH 4.5 acetate buffer, and desorption yield was found to be 97.4%. Cryogels were very stable, and it was found that there was no remarkable reduction in the adsorption capacity at the end of ten adsorption–desorption cycles. As a result, Reactive Green 19-attached cryogels have great advantages such as easy preparation, rapid adsorption, and desorption, being economic and allowing the direct separation of proteins.

Dye-attached cryogels for reversible alcohol dehydrogenase immobilization

In this work, poly(HEMA-co-GMA) cryogel was synthesized by using cryopolymerization technique and this cryogel was functionalized with Cibacron Blue F3GA dye. Prepared dye attached cryogel was used for the reversible immobilization of alcohol dehydrogenase from its aqueous solution. Cibacron Blue F3GA attached poly(HEMA-co-GMA) cryogel was characterized by environmental scanning electron microscopy (ESEM), energy dispersive X-ray (EDX) analysis and swelling studies. Surface morphology of the cryogel was considerably porous and the pore size was found to be around 30-50 μm. Effects of medium pH, initial alcohol dehydrogenase concentration, medium temperature and ionic strength on the alcohol dehydrogenase adsorption were also investigated and maximum alcohol dehydrogenase adsorption onto the dye-attached cryogel was found to be 8.55 mg/g cryogel. Adsorbed alcohol dehydrogenase was desorbed from the cryogel by using 10 mL of NaCl solution (1.0M; in pH 4.0 acetate buffer). Synthesized cryogel was able to reuse for 25 sequential cycles and it was found that, there was no negligible decrease in the adsorption capacity of the dye-attached cryogel.